The emerging role of cardiovascular MRI for risk stratification in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is the most common inheritable cardiovascular disorder. Although many HCM patients remain asymptomatic, sudden death (SD) can occur as the initial manifestation of the disease. It has been hypothesized that myocardial architectural disorganization and scarring represent an unstable electrophysiological substrate that creates susceptibility to malignant ventricular arrhythmias. Cardiovascular magnetic resonance imaging (CMR) is widely used for the diagnosis of HCM, especially in patients with an incomplete or inconclusive echocardiography study. CMR can provide precise non-invasive assessment of biventricular function, wall thickness, and assessment of myocardial fibrosis, using inversion recovery gadolinium-enhanced sequences. CMR is also one of the most promising avenues of research in HCM, and in recent years, has provided many new insights and identified a number of potential adverse prognostic indicators for SD. Future work is still needed to integrate CMR findings into traditional risk assessment algorithms. This paper reviews the evolving role of CMR for risk stratification in HCM including assessment of myocardial hypertrophy, fibrosis and ischaemia.

Pro-inflammatory cytokines IL6, TNF-alpha, IL1beta, procalcitonin, lipopolysaccharide binding protein and C-reactive protein in infective endocarditis.

OBJECTIVE: To evaluate the serum levels and diagnostic value of cytokines and acute phase proteins in patients with infective endocarditis (IE). PATIENTS AND METHODS: Serum samples from 63 patients diagnosed with IE and 71 control patients were analysed for the following markers: interleukin-6 (IL6), tumour necrosis factor-alpha (TNF-alpha), interleukin 1-beta (IL1beta), procalcitonin (PCT), lipopolysaccharide binding protein (LBP) and C-reactive protein (CRP). RESULTS: Serum levels of IL6, IL1beta and CRP were significantly elevated in patients with IE as compared to controls. PCT, TNF-alpha and LBP were not elevated. CONCLUSION: Serum CRP and IL6 are elevated in IE. IL 6 may aid in establishing the diagnosis. There was no correlation between IL 6 levels and CRP, causative microorganism, echocardiographic features or outcome.

Guidelines for the prevention of endocarditis: report of the Working Party of the British Society for Antimicrobial Chemotherapy.

These guidelines have been produced following a literature review of the requirement for prophylaxis to prevent bacterial endocarditis following dental and surgical interventions. Recommendations are made based on the quality of available evidence and the consequent risk of morbidity and mortality for "at risk" patients.

The serological diagnosis of staphylococcal infective endocarditis.

OBJECTIVES: Establishing the diagnosis of infective endocarditis (IE) can be difficult when blood cultures remain sterile or echocardiography is inconclusive. Staphylococcus aureus is a common aetiological microorganism in IE and is associated with severe valvular destruction and increased mortality. Early diagnosis using culture and antibiotic independent tests would be preferable to allow prompt antibiotic administration. We have developed and evaluated 2 serological assays for the rapid identification of a staphylococcal aetiology in infective endocarditis. The assays measure IgG against whole cells of S. aureus and IgG against lipid S, a novel extracellular antigen released by Gram-positive microorganisms. METHODS: Serum was collected from 130 patients with IE and 94 control patients. IgG against whole cells of S. aureus and against lipid S was measured by enzyme linked immunosorbent assay (ELISA). RESULTS: Anti-lipid S IgG titres were higher in IE caused by Gram-positive microorganisms than in controls (p<0.0001) and higher in staphylococcal IE than in both controls and IE caused by other microorganisms (p=0.0003). Anti-whole cell staphylococcal IgG was significantly higher in serum from patients with staphylococcal IE than in IE caused by other microorganisms and control samples (p<0.0001). CONCLUSION: High anti-whole cell IgG titres are predictive of a staphylococcal aetiology in IE. Elevated serum anti-lipid S IgG titres are predictive of Gram-positive infection compared to controls, very high titres being associated with staphylococcal IE.

Detection of bacterial DNA in cardiac vegetations by PCR after the completion of antimicrobial treatment for endocarditis.

PCR with broad-range primers for prokaryotic 16S rRNA genes was used to identify bacterial DNA in tissue from patients undergoing valve replacements following a previous episode of infective endocarditis (IE). Of eight valves investigated, bacterial DNA was detected in three from patients for whom IE had been treated by antibiotic therapy 5, 12 and 18 months previously. The demonstration of bacterial DNA within resected heart valves suggests either recurrence of infection, treatment failure or the persistence of bacterial debris within the cardiac vegetation. There may also be implications for routine use of PCR in the diagnosis of infection.

Evaluation of PCR in the molecular diagnosis of endocarditis.

OBJECTIVE: Infective endocarditis (IE) is diagnosed by the Duke criteria, which can be inconclusive particularly when blood cultures are negative. This study investigated the application of polymerase chain reaction (PCR) to identify bacterial DNA in excised valvular tissue, and its role in establishing the diagnosis of IE. METHODS: Ninety-eight patients undergoing valve replacement surgery were studied. Twenty-eight patients were confirmed as definite for endocarditis by the Duke criteria; nine were considered as possible and 61 had no known or previous microbial infection of the endocardium. A broad-range PCR technique was used to amplify prokaryotic 16S rRNA genes present within homogenised heart valve tissue. Subsequent DNA sequencing of the PCR amplicon allowed identification of the infecting microorganism. RESULTS: PCR results demonstrated the presence of bacterial DNA in the heart valves obtained from 14 out of 20 (70%) definite IE patients with positive blood cultures preoperatively. The causative microorganism for one patient with definite culture negative endocarditis was identified by PCR. Two out of nine (22%) of the valves from possible endocarditis patients also had bacterial DNA present converting them into the definite criteria whereas in the valves of seven out of nine (78%) of these patients no bacterial DNA was detected. CONCLUSION: The application of PCR to the explanted valves in patients with possible or confirmed diagnosis can augment the Duke criteria thereby improving post-surgical antimicrobial therapeutic options.

The microbial diagnosis of infective endocarditis.

This review suggests an evidence-based algorithm for sequential testing in infective endocarditis. It discusses blood culture and the merits and drawbacks of serology in making the diagnosis. Newer techniques are briefly reviewed. The proposed algorithm will complement the Duke criteria in clinical practice.

Haemophilus paraphrophilus prosthetic valve endocarditis.

We report a case of prosthetic, aortic valve, infective endocarditis caused by Haemophilus paraphrophilus. There are no other cases described in the available literature where this microorganism has caused prosthetic valve endocarditis and no other case reported involving only the aortic valve.

Eikenella corrodens infective endocarditis in a previously healthy non-drug user.

Reported here is a case of Eikenella corrodens aortic valve infective endocarditis presenting as a stroke in a previously healthy 31-year-old man. The patient had no evidence of structural heart disease and reported no history of intravenous drug use or recent dental treatment. There are no other cases reported in the available literature in which this microorganism has caused endocarditis in the absence of recognised risk factors.